.audio-button {
  position: fixed;
  z-index: 9999;
  background-color: #000;
  color: #fff;
  padding: 12px 15px;
  border-radius: 50%;
  font-size: 18px;
  cursor: pointer;
  box-shadow: 0 0 10px rgba(0,0,0,0.3);
}
.audio-button.bottom-right { bottom: 20px; right: 20px; }
.audio-button.top-right { top: 20px; right: 20px; }
.audio-button.bottom-left { bottom: 20px; left: 20px; }
.audio-button.top-left { top: 20px; left: 20px; }